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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount of stock repurchase plan authorized.

+ References

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- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

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- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

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-Name Accounting Standards Codification
-Topic 505
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-Section S99
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Earnings per Share Share Repurchase (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Oct. 25, 2018	Sep. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Class A Common Stock repurchased		3,599,107	44,114
Average stock price of Class A Common Stock repurchased	$ 87.46	$ 75.99
Stock Repurchased and Retired During Period Weighted Average Basic Shares Impact	301,000	1,707,000
Share Repurchase Program 1 [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 300,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 29,500	$ 29,500
Class A Common Shares [Member] \| Share Repurchase Program 1 [Member]
Equity, Class of Treasury Stock [Line Items]
Class A Common Stock repurchased	894,000	3,560,000
Subsequent Event [Member] \| Share Repurchase Program 1 [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 0
Subsequent Event [Member] \| Share Repurchase Program 2 [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 500,000